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Top Speed Estimate

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Old 11-09-2010, 02:19 AM
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Car: 84 Trans AM
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Top Speed Estimate

Just wondering exactly how fast my car can go. The 85 mph speedo is of no help. I've got an 84 TA, carbed 305 LG4, edlebrock rpm intake, headers and full exhaust no cat, no emissions, no computer, Holley 600 CFM carb, vacuum advance dizzy, 700 r4 automatic with 3.4 rear end ratio, and a good tune. Any guesses??
Old 11-09-2010, 05:27 AM
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Re: Top Speed Estimate

150 mph going off a cliff.
65 mph going up hill.
95 mph going on a flat.

Im not really helpful lol. You dont have a high hp engine, its more tourqey than anything, its not going to "go" real fast, its more for accelerating than top speed.
Old 11-09-2010, 10:53 AM
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Re: Top Speed Estimate

Originally Posted by Dr. Phil
150 mph going off a cliff.
lolololol
Old 11-11-2010, 02:06 AM
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Re: Top Speed Estimate

Lol, next time I get pulled over for speeding and the cop goes do you know how fast you were going? I'm going to be like, look I wasn't going off a cliff or any thing!!!
Old 11-11-2010, 02:52 PM
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Re: Top Speed Estimate

Hmm, idk your power levels, but I just go by the IROC-Z top speed, which was 155 or 149 I think, basically just figure that you have the same, or in your case slightly better aerodynamic profile...so IROC-Z puts out 225 hp I think for a 350 tpi, so lets say you're making like...150 hp, you would probably do 120-130.

Honestly though, not my fault if you crash and burn/die or get a ticket, but if you have a GPS unit, alot of them can display your current speed...thats how I found out what my lumina and buick century topped out at...both were governed sadly 106 and 110 respectively...my Camaro pushing about 200hp and 240 tq could probably do 140 if it had 4th, but 700r4 won't shift into 4th at WOT in the v6 car, maybe v8 too, not sure, but since I am naturally limited by being stuck with 3rd gear, it will top out at 120.

So if you're deadset on knowing exactly...buy a cheap used gps that has that feature if you don't have one, also some smartphones have gps, maybe they can track speed too if you have one of those, also you could swap out the speedo, its honestly not alot of work or money...
Old 11-11-2010, 04:11 PM
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Re: Top Speed Estimate

Don't know if this helps, but I topped off at 130 with everything stock (LG4, single snorkle, stock exhaust, 165-170 h.p.) before I began to mess with everything. Mind you, it took a long stretch of empty road and a well maintained car and a buddy following me with his car which had a speedometer that was over 130.

I was in my early 20's and would not do that again. It was fun but dangerous too. Take it to a track where you can get it timed and clocked in a controlled environment if possible.
Old 11-11-2010, 09:01 PM
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Re: Top Speed Estimate

given a 27 in tall tire 3.40 gears and the trans in 3rd gear not overdrive and a redline of 5500 RPM your top speed would be about 130 MPH
here is a useful tool that can help you find out any top speed calculations
http://www.csgnetwork.com/speedcalc.html
Old 11-11-2010, 09:23 PM
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Re: Top Speed Estimate

You'll probably hit a wall speed wise about 120mph. Anything after that will take a LONG time. Most 700r4 equipped cars can't apply full throttle in 4th gear, without the automatic downshift to 3rd. I'd say your gearing will run out about 140mph, but you probably won't exceed 130mph.

Aerodynamic drag build quickly past 80mph.

At Road America I was taking it easy and I had my G6 GTP up to 115mph. Pushing it hard would probably net 120-125mph. C6 Z06's were doing about 165mph at the end of the 4,000ft straight.

The GTA will easily exceed 120mph. The standing mile would be about 150mph or so. A stock L98's standing mile is about 140mph.

Last edited by Thirdgen89GTA; 11-11-2010 at 09:34 PM.
Old 11-11-2010, 09:28 PM
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Re: Top Speed Estimate

Originally Posted by HF_monster
given a 27 in tall tire 3.40 gears and the trans in 3rd gear not overdrive and a redline of 5500 RPM your top speed would be about 130 MPH
here is a useful tool that can help you find out any top speed calculations
http://www.csgnetwork.com/speedcalc.html

that is the physical limitations, it would not do 140 under those parameters, and 27" tall tire sounds an " too high, I recall both my 75 wall 14s, and my 60 wall 16s being about 26, also 3.40 is not the correct gear ratio...its technically 3.42.
But without 4th gear or raised redlines these cars tend to be somewhat limited in top speed by factors other than the engines when sufficient power is available.
Old 11-12-2010, 10:42 PM
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Re: Top Speed Estimate

Originally Posted by 3rd gen RS

that is the physical limitations, it would not do 140 under those parameters, and 27" tall tire sounds an " too high, I recall both my 75 wall 14s, and my 60 wall 16s being about 26, also 3.40 is not the correct gear ratio...its technically 3.42.
But without 4th gear or raised redlines these cars tend to be somewhat limited in top speed by factors other than the engines when sufficient power is available.
I've never had a 700r4 that wouldn't make the 3-4 WOT upshift STOCK.

My 305 TPI had swirl port heads, LT4 roller cam, and doug thorley headers at the time. In a 5,600 lbs G-van. WOT shifts were around 5,500 rpm. 26" tall tires (275/40/R17) and 3.08 gears. 2nd gear pull from 25 mph on flat land through the WOT 3-4 upshift. Roughly 130 MPH, took roughly a mile.


Last edited by Fast355; 11-12-2010 at 10:51 PM.
Old 01-03-2011, 08:48 PM
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Re: Top Speed Estimate

I have an 88 IrocZ 700r4 L98 350 and mine will upshift 3-4 with 3/4 throttle not WOT somewhere between 120-130mph.

Last edited by chevyredneck8; 01-03-2011 at 09:00 PM.
Old 01-04-2011, 12:20 AM
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Re: Top Speed Estimate

I have an LG4 with 700r4, no upgrades yet, and I was driving my friend from college in Indianapolis to Kansas City, Missouri for a trip to his family's. We had his GPS with us and after the spedometer went past 85 we'd check the GPS to see how fast it stated we were going. I got it up to 105 and it started to shake some in the front end so I slowed back down to 80-85. I was begging for a cop to pull me over and ask "Do you know how fast you were going?" so I could say "No officer, as you can see the spedometer stops at 85".
Old 01-04-2011, 06:12 AM
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Re: Top Speed Estimate

Good edit, cause I don't think your story was even close to being the closest
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